1. Field of the Invention
The present invention relates to a fan motor.
2. Description of Related Art
A fan motor is known and is disclosed in, for example, US 2004/0223845A1. In the fan motor of US 2004/0223845A1, a rotatable shaft is provided in a drive motor unit of an inner rotor type, and a fan is connected to the rotatable shaft. The fan has a cup-shaped fan boss. A plurality of blades is provided to an exterior of the fan boss, and a plurality of fins is provided in an interior of the fan boss. Furthermore, a plurality of cooling holes is provided in a bottom portion of a motor housing of the drive motor unit. When the drive motor unit is energized to rotate the rotatable shaft, the fan boss is rotated relative to the housing of the drive motor unit to rotate the blades and thereby to create an air flow for cooling a radiator of a vehicle. At this time, another cooling air flow is also created by the fins of the fan boss to flow from an interior of the housing of the drive motor unit to the outside of the housing of the drive motor unit through the cooling holes.
However, in the fan motor disclosed in US 2004/0223845A1, although the cooling air flow is created by the fins of the fan boss to flow from the interior of the housing of the drive motor unit to the outside of the housing of the drive motor unit, a flow quantity of the cooling air flow, which passes the interior of the housing of the drive motor unit, is relatively small. Thus, the interior of the drive motor unit cannot be effectively cooled.